In many parts of the country, natural gas as produced contains undesirably high quantities of water. In order to meet pipeline specifications, this wet gas must be dried. A common technique involves contacting the wet gas with a stream of glycol, usually triethylene glycol. The water is absorbed by the glycol. The wet glycol stream is then heated in a regenerator to drive off the water to the atmosphere and the dried glycol is then cooled and recirculated to remove additional water. The equipment for contacting the glycol and the wet gas and for drying the glycol is mechanically simple and, for smaller applications, is self-regulating after initial manual adjustment and does not require electrical power or a source of water. Many units of this type equipment are used in remote locations to dry gas from remotely located wells.
Such gases also frequently contain light aromatic hydrocarbons such as but not limited to benzene. These light aromatic hydrocarbons are also strongly absorbed by glycol. These light aromatic hydrocarbons are then driven off with the water vapor in the regenerator and discharged to the atmosphere with the water vapor. Fifty to one hundred tons per year of benzene may be released to the atmosphere from a typical unit.
A continuing effort has been directed to efforts to prevent the escape of this light aromatic hydrocarbon material into the atmosphere while still providing a unit which can operate at remote locations without the need for electrical power or water.